1. Field of the Invention
This invention relates to an electronically controlling, fuel injection method for an automotive engine, in which a gasoline fuel containing alcohol is employable.
2. Description of the Prior Art
Alcohol and gasoline differ from each other in a stoichiometric air-fuel ratio. For this reason, when a gasoline fuel containing alcohol is used, there occurs divergence in an air-fuel ratio from a required value, particularly in open loop controlling in which an air-fuel-ratio-feedback signal is cut off, such as during the warming-up of an engine and when a throttle valve assumes a fully open position. This leads to the lowered operational performance of the engine as well as an increased amount of detrimental constituents released to atmosphere.
Furthermore, in an electrostatic capacity type alcohol sensor for detecting a concentration of alochol in a fuel, an output of the sensor fluctuates due to alcohol as well as due to impurity, such as water, and its output tends to change with the lapse of time. Due to these factors, a proper air-fuel ratio is hardly obtainable, although an amount of fuel being injected is calculated on the basis of a concentration of alcohol.